This may happen for several reasons. Follow the steps below to isolate the issue.
- If you're trying to connect via the server's DNS name: Try the IP address instead. If you can connect via the IP address, then correct the DNS entries on your DNS server.
If connecting remotely from another client or server: Make sure TCP port numbers 660, 687, 311 are not being blocked.
- Ensure servermgrd is running on the target server. You can use Activity Monitor locally on the server. Or, you can open an ssh session to the server, then execute the following command:
ps aux | grep servermgrd
- If servermgrd is not running you can start it by running the following command on the server:
sudo launchctl load -w /System/Library/LaunchDaemons/com.apple.servermgrd.plist
- Check Server Admin's preference setting "Require valid digital signature(SSL)". If it's checked (enabled), uncheck it and try again. If it's not enabled, enable it and try again.